Location

La Jolla, CA

Start Date

1-1-1987 12:00 AM

Description

Difficulties often occur in eddy current inspection when a defect is situated close to an edge. This is due to the large signal arising from the edge (‘edge-effect’) which tends to obscure any signals coming from the defect [1,2]. To understand the edge-effect in eddy current NDI in more detail, the induction of eddy currents in a conducting 90° edge by a two-dimensional coil is considered in this paper. Firstly, the impedance of a two-dimensional coil in the vicinity of a conducting quarter-space is calculated numerically using a dual boundary-integral-equation (BIE) method and the results compared with experiment. The behaviour of the induced currents (vector potential) in the vicinity of the edge is then examined using the numerical (BIE) results and the results of an analytical approximation [3] valid in the limit of small skin-depth.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

6A

Chapter

Chapter 1: General Techniques—Fundamentals

Section

Eddy Current

Pages

169-175

DOI

10.1007/978-1-4613-1893-4_19

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Eddy Current Induction by a Coil near a Conducting Edge in 2D

La Jolla, CA

Difficulties often occur in eddy current inspection when a defect is situated close to an edge. This is due to the large signal arising from the edge (‘edge-effect’) which tends to obscure any signals coming from the defect [1,2]. To understand the edge-effect in eddy current NDI in more detail, the induction of eddy currents in a conducting 90° edge by a two-dimensional coil is considered in this paper. Firstly, the impedance of a two-dimensional coil in the vicinity of a conducting quarter-space is calculated numerically using a dual boundary-integral-equation (BIE) method and the results compared with experiment. The behaviour of the induced currents (vector potential) in the vicinity of the edge is then examined using the numerical (BIE) results and the results of an analytical approximation [3] valid in the limit of small skin-depth.